I must add that prior to this incident, the cord had been yanked violently by a moving chair and the device pulled from a low surface onto a wooden floor. Obviously this severely weakened the solder joints, so I certainly recommend caution (as always) with devices connected to cables of any kind.

I now feel your pain. My micro USB port has disconnected and is now loose inside the N900 and I can't use for charging or anything else anymore. Unlike you though, I had no violent pulls. I just started noticing that plugging it into a computer resulted in it sometimes not recognizing that it was plugged in. I would have to plug it in a few times before it would start charging. I was always perfectly careful when inserting or removing the micro USB cable... so this makes me think there might be a design problem in the N900.

I'm afraid to see if there's going to be a huge wave of returns/repairs in two months due to this issue. :/